Include helm chart removal in detritus cleanup

admin/cleanup-test-detritus.sh

 #!/bin/bash -e
+for potato in $(helm list -n geosphere-test |perl -ne '/^(test-\S+)/ && print "$1\n";'); do 
+  helm uninstall -n geosphere-test $potato
+done
 for api in deployment.apps statefulset.apps job.batch cronjob.batch service pod; do 
   for item in $(kubectl -n geosphere-test get all |egrep ^${api}/test |cut -d ' ' -f1); do 
     kubectl -n geosphere-test delete $item